In a subclan aery block at outer border of 1st rib, all of the following aeries help in maintining the circulation to upper limb except?

Superior thoracic aery[Ref: BDC 4/e, Vol 1, p 56, 82; Snell's Clinical Anatomy 6/e, p 412-413, 657; Moore Clinical Anatomy 5/e, p 766-767JA rich anastomosis exists around the scapula between branches of subclan aery (first pa) & the axillary aery (third pa).This anastomosis provides a collateral circulation through which blood can flow to the limb when the distal pa of subclan aery or the proximal pa of axillary aery is blocked.Anastomosis around the scapula : Formed by branches of?Subclan aery - first pa - Suprascapular aery - Deep branch of transverse cervical aeryAxillaty aery - third pa - Subscapular aery & its circumflex scapular branchThere are other smaller anastomoses over the acromion process, which also helps to maintain .11ow to arm. (BDC Vol 1, 4/e, p 82)Anastomoses over the acromion process: Formed by -a)Acromial br. of thoraco-acromial aeryb)Acromial br. of suprascapular aeryc)Acromial br. of posterior circumflex humeral aeryThe subscapular aery also forms anastomoses with intercostal aeries.Review of subclan & axillary aery: The subclan aery is divided into 3 pas by scalenus anterior muscle; the l' pa is proximal to the muscle; 2" pa is posterior; and the 3rd pa is distal to the muscle upto outer border of the first rib, after which it becomes the axillary aery.The axillary aery, a continuation of the subclan aery, begins at the outer border of the first rib, and ends at the inferior border of teres major where it becomes the brachial aery. Pectoralis minor crosses it and divides it into three pas which are proximal, posterior and distal to the muscle.